Apparatus for electric arc welding



1949- N. G. SMITH APPARATUS FOR ELECTRIC ARC WELDING Filed Feb. 16, 1948 Patented Aug. 2, 1949 znwsot APPARATUS i on ELECTRIC ARC WELDING his essay Sinith, Goteborg, Sweden, s-signer to Elektri'ska vctsningsalrtiebol'agt; Goteborg, Sweden; a corporation of Sweden Application February 16, 1948, Serial No; 8 666 In Sweden December 19, 1946 section 1, Public Law 690. August 8,1946

5 Claims. 1

This invention relates to welding apparatus for so-called semi aut'om'a'tic arc welding with rod-shaped coated electrodes. More particu larly the invention relates to electric welding apparatus of the general type comprising a car'- rier member adapted to move in a predetermined course towards the work to be welded, and an electrode holding member, or socket member, attached to said carrier in such manher that an electrode mounted in said socket member will extend at an angle to the seam to be welded, said carrier member being operated by a mechanical force urging the same towards the work, whereby the electrode tip is maintained in engagement with the welding seamdur ing the gradual melting of the electrode. The carrier member may be for instance a lever turning about a fulcrum, or a carriage guided in a linear path, and the force acting upon said carrier member maybe its own weight. By the use of two (or more) such apparatus it is possible to provide for automatic changeover from a used-up electrode toa fresh one. To that end, one apparatus having the fresh electrode mount ed therein is placed in front of the other apparatus in such position that the tip of the fresh electrode is situated at the point or the welding seam in which the rear electrode will be finished; The electrodes may be connected to a common source of current, or preferably to individual sources of current (tran-sformers'oi' generators). By this means the fresh electrode will be auto matically started by the one about to be finished. If, however; the electrode's'form too acute an angle with one anotherand with the work piece, starting of the fresh electrode will sometimes fail to occur-,owing to the fact that the are of the used-up electrode does not get sufficiently close to the tip of the fresh electrode. It may also happen that, even if starting occurs according to plan, the welding will be irregular owing to insufficient supply of molten electrode metal to the portion of the joint intermediate the points atwhich the finished electrode stops and the fresh electrode starts.

The invention has'for its'.-prineipal purpose to improve the apparatus of the type above referred to in such manner as to remove or reduce its present disadvantages. Aecord-ing to the inverttion, the socket member, or electro'de holding '2 member, is attached to the carrier member through a joint adapted to allow of rotation of the electrode holding member in a plane through the welding seam, ineans being provided for opposing such rotation in the direction of the couple acting upon the electrode holder on engagement between the electrode tip and the work; furthermore, means are provided for checking the movement'of the carrier member towards the work as soon as the electrode has burned down to a stub of predetermined length.

The invention shall now be explained with reference to the accompanying drawing, in which Fig. 1' is'a plan view of one form of the apparatus according to the invention shown in its starting position.

Fig. 2 is a corresponding elevation,

Fig. 3 is a detail elevation of the electrode holder member and theadlaeent portion of the carrier member shown in' the position they will have when the electrode is'nearly finished.

Fig. 4 is an elevatlon'al'view similar to Fig. 3 showingthe parts in the moment the electrode has arrive'dto the end of its travel.

Fig; 5 is a detail'elevational view in larger scale of the elect-rode holder member and the joint in a somewhat modified form of the apparatus.

The apparatus shown in Figs; 1 to 4 comprises a support or standard" I, a carrier member 3 constitute'd by a lever'hinge'd at one end'to the top of the'st'andard' I through a bolt 2, a joint formed by disc 6 rigl'dl y attached to the lever 3 and disc 7 rotatabl-y connectedto disc 6, and an electrode holder 4 attacnedto; but electrically insulated from thedis'c '1. The standard I is provided with a base plate i restingon the work with four screws 8. The lever 3 is provided with a rodshaped stop member lu'the upper part of which forms a screw engaging a threaded bore in the lever 3 and having a knurled head II by means of which the vertical position of the stop memher [0 may be adjusted. The disc 5 is provided with a pair of laterally pro ecting studs 12, 53 serving as stops cooperating'with a radial projeetion l4 o'f'the disc I so as to define a predetermined angular rahge'within which the disc '5 with electrode helde'r are movable. The 61s"- trode l5'is contested tesup'pit cable iii through connecting terminal I! and pliable conductor link 9. e

A second electrode l8 shown with dotted lines is placed with its tip resting against the work at the point of the welding seam which forms the termination of the path of the electrode 15, that is, the point at which said electrode is consumed down to a stub which cannot be utilized. Said second electrode I8 is assumed to be fitted in a second apparatus (not shown) of the same type as the one just described.

The welding will proceed as follows. The are from the electrode I is struckin the usual way, for instance by inserting a conducting object between the bared core and the work, or by subjecting this point to the flame of a torch. During the first (and longest) part of the subsequent period during which a gradual fusing of the electrode occurs, the lever 3 and the holder 4 with electrode [5 will behave as a rigid system, as the couple created by the reaction from the work upon the electrode tip will maintain the projection M in stable engagement with stud 12. The position of said stud and the inclination of the electrode l5 resulting therefrom are so chosen that a predetermined amount of electrode metal is fused per unit of length of the welding seam. In the embodiment shown, the design is such that said ratio is constant during the entire period in which projection I4 remains in engagement with stud I2. When the welding has progressed so far that the electrode I5 is nearly exhausted, the bar to enters into engagement with the work, thus preventing further downwards movement of the lever 3. This phase is illustrated in Fig. 3. The melting of the electrode I5 will, however, progress a little further owing to the fact that the electrode holder 4 and the disc I are free to rotate on disc 6 under the action of the weight of the electrode holder 4 and the electrode stub 15. The electrode tip will therefore continue its travel along the welding seam and eventually reach the tip of the second electrode 3 (see Fig. 4). It will be noted that by the arrangement described the angle formed by the electrodes 15 and i8 when engaging one another is much greater than it would have been if the electrode 15 had not been free to rotate with regard to the lever 3. This feature will facilitate starting of the fresh electrode, and the fact thatthe tips of the electrode cores may be brought into close relation to one another will also result in an even, or substantially even supply of additional metal to the welding joint. The angle between the electrodes in the position illustrated in Fig. 4 will depend on the position chosen for the tip of the new electrode l8 in relation to the apparatus in which the first electrode (I5) is held and may thus within limits be adjusted at will.

The progress of the change-over of the are from one electrode to the other will to some degree depend on whether the welding apparatus are connected to one and the same source of welding current or to individual sources of current (e. g. welding transformers). At least in the second case the are from the exhausted electrode will continue burning for a while after the new are has been struck. The projection 53 shown will check the travel of the electrode it, thus preventing an excessive supply of additional metal to the welding seam.

In the modified embodiment illustrated in Fig. 5, the studs I2, I 3 have been replaced by projections I9, 20 supporting stop screws 2! 22, by which the range of angular movement of the disc 7 may be adjusted.

It should be expressely pointed out that the above description is intended to explain the principle of the invention only, and that the devices referred to may be modified and supplemented in many respects within the frame of the invention. Thus, the carrier member 3 does not have to be a lever, but may take the shape of a slide or like member with parallel motion. The bar it may be replaced by any other stop member suited to check further movement of the carrier member 3 as soon as the length of the electrode M has decreased to a predetermined value. The lever 3 or the standard I may for instance be provided with an adjustable stop screw cooperating with a portion of the standard or the lever, respectively.

The stud It or stop screw 22 may be dispensed with, as the device may operate satisfactorily without any particular means for limiting the final rotation of the electrode holder about its joint.

The studs l2, l3 or stop screws 2|, 22 may of course be replaced by any other stop members suitable for limiting the rotation of the electrode holder. At least the stop member serving to maintain the holder in the correct position during the phase immediately following upon the starting of the electrode held therein should preferably be adjustable. As a rule, the range of angular movement between the stop members should be smaller than 45 degrees, e. g. 15 or 20 degrees.

Particularly in welding with thin electrodes having comparatively small weight it may be necessary or advisable to provide special means for rotating the electrode holder 4 with regard to the carrier member 3, for instance a weighted lever attached to said holder, or an extension spring acting between the lever 3 and the electrode holder 4. According to another possibility, the bar I!) connected to the lever 3 is replaced by a bar depending from a pivot pin provided on the right half of the disc I. Said link then exercises the double function of limiting the downward movement of the lever 3 and producing an extra torque on the holder 4.

If the apparatus is to be used for vertical welding or downhand welding, the lever 3, or the member corresponding thereto, has to be provided with special means, e. g. a spring extended between the lever and the standard I, or a weighted lever, for securing the required contact pressure between the electrode tip and the work.

The above description of various modifications or embodiments of the invention is in no way exhaustive, the purpose thereof being only to give some suggestions regarding the many ways in which the apparatus according to the invention may be adapted to the varying conditions and desiderata occuring in welding work.

1. Apparatus for electric arc welding seams with rod-shaped coated electrodes, comprising a carrier member, means for guiding said carrier member in a predetermined course directed generally towards the work to be welded, an electrode holding member, a joint connecting the electrode holding member to the carrier member in such manner as to allow of rotation of the electrode holding member in a plane through the seam to be welded, stop means for opposing such rotation in the direction of the couple acting upon the electrode holder an engagement between the electrode tip and the work, and stop means for restricting the movement of the carrier member towards the work, said last-mentioned stop means 5 being so positioned as to come into action when a short length only of the electrode remains.

2. Apparatus according to claim 1 in which the means for restricting the movement of the carrier member is adjustable.

3. Apparatus according to claim 1 in which the means for restricting the movement of the carrier member is adapted to engage a portion of the work adjacent to the welding seam.

4. Apparatus according to claim 1 and in which a stop means is provided for limiting rotation of the electrode holding member about the joint in the opposite direction as well.

5. Apparatus according to claim 1 and in which an adjustable stop means is provided for limiting 15 2,422,811

rotation of the electrode holder member about the Joint in the opposite direction as well.

NILS GUSTAV SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,204,545 Faunce June 18, 1940 2,370,716 Carter Mar. 6, 1945 2,421,095 Tyrner May 27, 1947 Tyrner June 24, 1947 

